Manufacture of viscose rayon



MANUFACTURE (IF VISCOSE RAYDN Aart Buurman, Velp, and Robbert Alden-t Vroom and Pieter Coenraad Limhurg, Arnhem, Netherlands, assignors to American Enka Corporation, Erika, N.C., a corporation of Delaware No Drawing. Filed Dec. 24, 1956, 52:. No. 630,033 Claims priority, application Netherlands Jan. 16, 1956 8 Claims. (CI. 18-54) This invention relates to the manufacture of viscose rayon and more particularly to an improvement in the viscose process and improved cellulosic products produced therefrom.

In the viscose rayon industry today it is rather common practice in the production of yarns having very high tenacity to retard or modify the regeneration process of the cellulose. This is done by adding certain chemicals either to the acid spinbath or to cellulose base material at some stage in the production of viscose prior to extrusion which retard the regenerating of the cellulose. These chemicals have become known in the art as viscose modifiers.

By using a modifier it is possible to produce yarns having a very high strength and improved soil and abrasion resistance. Furthermore, the cross-section of the modified yarns reveals filaments which have substantially 'all skin and very little, if any, sensitive core and which have peripheries of notably reduced crenulations. Also, the modified yarns are characterized by greater toughness, greater fatigue resistance and reduced gel swelling.

Although the general idea of chemically modifying the coagulating-regeneration process in the production of viscose rayon is old, the problem of selecting the most desirable modifying agent is by no means simple. Some of the considerations given in selecting a modifier include consideration of price, ease in preparation, commercial availability, solubility in viscose and solubility in spinbath. But the most important consideration to be given is the effect it has on the yarn produced. For example, one type of modifier may influence the production of an all skin yarn which may be very brittle. In other Words, the flex-life of the yarn may be sacrificed for a gain in tenacity. Therefore, a need for a modifier which is effective in producing a modified yarn having the most optimum balance of the possible modifying efiects exists in the industry today.

In US. Patent No. 2,593,466 it was disclosed that by incorporating into the viscose at any stage of its preparation about 0.01 to 0.2% by weight of a product formed from the reaction of at least about 12 moles of alkylene oxide with ,1 mole of a primary or secondary aliphatic amine or mixture thereof, the amines containing from 6 to 18 carbon atoms, certain spinning difiiculties could be overcome. However, viscose modification at the time was not known in the art, and the amine was used for an entirely difierent purpose, namely, to prevent clogging of the spinneret orifices.

One of the most promising class of modifiers is a type of organic compound which contains a polyoxyethylcne "structure. Many of these compounds of this type have been suggested. Such substances include castor oil condensed with alkylene oxide, residual oil of sulfitic liquors from wood pulp condensed with alkylene oxide, urea condensed with alkylene oxide and phenol condensed with alkylene oxide.

In another known process, as disclosed 1n British Patent No. 741,728, a viscose modifier with the general formula,

atent 2,970,883 Patented Feb. 7, 1961 RO--(C H O),,R in which R represents an alkyl or an aryl radical and R represents an alkyl radical, an aryl radical or hydrogen and n is a number of four or less is suggested as an agent to modify the formation of rayon so that threads having a lower swelling value and a greater skin area as compared with filomentous products produced from unmodified viscose may be formed.

Furthermore, it has previously been found that threads with an increased skin character and a. lower swelling value may be manufactured from viscose when the regeneration of the cellulose is carried out in the presence of a polymer, copolymer or block polymer of epoxyalkanes or their substitution products.

However, a notable disadvantage connected with the known polyoxyalkylene type of viscose modifiers is that optimum results can only be secured by strictly controlling the number of alkylene oxide units present in the modifier which is indeed expensive and difficult to do.

An object of the present invention is to provide a process for the manufacture of regenerated cellulosic products having improved properties such as high tenacity and high fatigue resistance suitable for use in high tenacity industrial cords and better textile fabrics.

Another object of this invention is to provide a process for regenerating cellulose filaments, films and the like which are modified in a spinbath.

A further object of this invention is to provide a viscose modifier which exerts an optimum modifying efiect upon the coagulation and regeneration of cellulose in a spinbath.

Still another object is to having improved properties.

It is further an object of this invention to provide both provide a cellulosip material a viscose solution and viscose spinbath containing a viscose'modifier whereby a product of enhanced properties is obtained.

A general advance in the art and other objects which will appear herein are also contemplated.

In accordance with the present invention, viscose of desired ripeness is extruded through a spinneret into a Zinc-containing acid spinbath in the presence of an organic compound containing alkylene oxide units which exert a decided modifying effect on the coagulation and regeneration process occurring in the bath. By incorporating in the spinbath or in the viscose at any stage of its preparation or both from 0.01%1.0% by weight of one or more of the compound comprising an organic radical (R with not more than 7 carbon atoms bound to one or more -(RO) -RR radicals, wherein R represents an aliphatic radical with two or more carbon atoms and R represents an organic radical with not more than 7 carbon atoms or a hydroxyl group and wherein n represents a whole number of at least 10, the regeneration-coagulation process is modified in a remarkable manner to produce regenerated cellulosic filaments, yarns, films and the like exhibiting improved properties. It is preferred that the ratio of the acid content in the spinbath to the alkali content in the viscose be about 1.3 to 0.8.

The organic radicals R and R may consist of alkoxy, aryloxy, thio-alcohol, thiophenol, acyloxy and acyl imino radicas. Furthermore, compounds may be used which are produced by the condensation of alkylene oxide with aldehydes, ketones, esters and isocyanates. However, the limiting condition is that the number of carbon atoms in said organic radicals should not exceed 7 because it has been found that with a larger number of carbon atoms the modifying effect of the polyalkylene oxide structure notably decreases.

One of the advantages of the present invention is that the number of alkylene oxide units is not critical. The modifier according to the present invention may contain preferably more than 10 alkylene oxide units with no definite restriction on the upper limit. Compounds containing 100 and more units have been found to be effective as a modifier.

Another disadvantage connected with the use of known polyoxyalkylene type of viscose modifier is that there is a tendency of the viscose containing the modifier to foam during the deaeration of the viscose. This foam is high- 1y undesirable since it impedes the deaeration process and may foam to such an extent that viscose may enter the vacuum conduits which make it necessary to limit the amount of viscose which may be deaerated in a tank of given size. Also, the foam is difficult to destroy. If foamy viscose is spun, the yarn quality is very poor and filamentary breaks occur quite frequently in the spinning process.

An unexpected advantage of the modifiers according to the present invention is that there is no foaming problempresent during the deaeration of the viscose when the modifier has been incorporated in the viscose prior to deaeration.

Examples of compounds in their structural formulae which have been found particularly useful are:

Of the foregoing compounds the reaction products of alkylene oxides with aldehydes and ketones may be especially attractive because they are stable in the viscose but are decomposed by acid. Thus, said compounds will be decomposed and will not build up in the spinbath to an undesirable amount.

Generally the best yarn is obtained when the spinbath contains at least 3% by weight of a zinc salt and the acid content in the spinbath is not over 7% by weight. Besides the acid and the zinc salt, the spinbath may also contain other usual substances such as sodium sulfate or magnesium sulfate. The quality of the yarn may be further improved if the;spun yarn is treated in the conventional two bath system in which the yarn is stretched 4 about 100% in the second bath. The stretching gives the threads a low swelling value.

The following examples illustrate methods carried out in accordance with the invention and are not to be construed as limitative.

Example I A viscose with a cellulose content of 7.3% and an alkali content of 5.5% and containing 0.1% of a compound With the formula,

was extruded through a spinneret in the usual manner into a primary spinbath. The viscose had a xanthate ratio of 0.49, a viscosity of 45 see. by the falling ball test and a ripeness of 15 Hottenroth. The spinbath contained 5.6% H 16.4% Na SO and 5.0% ZnSO and had a temperature of 62 C. For the purpose of increasing the spinning speed, the threads were directed in the primary spinbath through a two-diameter tube spinning device as described in the copending application, Serial No. 556,256, now Patent No. 2,908,937, assigned to the same assignee as the present application. The yarn was then directed in the usual manner into a second bath having a temperature of C. and having an acid concentration of about one-twentieth of the first spinbath. During the travel in the second bath the yarn was stretched with the final draw-off speed being 80 meters per minute. The yarn was aftertreated in the usual way.

The two-diameter tube comprised a tube of two different diameters, the inlet opening of which having a fiat trumpet-shaped flange disposed 2 cm. from and coaxially with the spinneret. The diameter of the tube portion closer to the spinneret was 21.5 mm. with the second portion being 26 mm. The length of the narrow and the wide tube portions were 40 and 14 cm., respectively. A frusto-conical tube portion with a length of 6 cm. formed the connection between the tube portions.

Physical properties of the yarn so manufactured were: the secondary swell value was 68% (i.e., the percentage of water retained in centrifuged yarn that has been- Example II A viscose with a cellulose content of 8.3% and an alkali content of 4.6% and containing 0.2% of the organic compound with the formula,

was extruded through a spinneret in the usual manner into a primary spinbath having a temperature of 50 C. The viscose had a xanthate ratio of 0.42, a viscosity of 35 see. by the falling ball test and a ripeness of 9 Hottenroth. The said spinbath contained 4.0% H 80 17.5% N21 SO and 3.3% ZnSO After leaving the spinbath, the spun threads were stretched 65% in air and taken up in the conventional way at a velocity of 55 meters per minute. The yarn was then aftertreated in the usual way.

Physical properties of the yarn so manufactured were: the secondary swell value was 70%; the dry elongation and wet elongation were 32 and 36 respectively; the dry strength and wet strength were 3.1 and 2.4-g./denier, respectively, with the wet strength being relatively high With regard to the dry strength; fabric made from the yarn exhibited excellent laundering properties; and the 'tially all skin.

cross sections of the threads showed a yarn of substan- Example III A viscose with a cellulose content of 5.5% and an was spun through a spinneret in the usual manner into a primary spinbath. The viscose had a xanthate ratio of 0.50 and a viscosity of 100 sec. (falling ball test). The said spinbath contained 4.8% H 80 18% Na SO and 4.0% ZnSO and had a temperature of 60 C.

The yarn was directed out of the first bath into a second bath having a temperature of 90 C. and containing 2% H 80 In the second bath the yarn was stretched 100%. The yarn was aftertreated in a conventional continuous process. The production speed of the yarn was 45 meters per minute.

Physical properties of the yarn so manufactured were: the secondary swell value was 65%; the dry strength was 4.9 g./denier; the dry elongation was 14%; the yarn made into tire cords showed excellent fatigue resistance; and the cross sections of the threads showed a yarn of substantially all skin.

Example IV A viscose with a cellulose content of 10.5% and an alkali content of 6.0% and containing 0.12% of a compound with the formula,

- was extruded through a spinneret in the usual manner into a primary spinbath.- The viscose had a xanthate ratio of 0.39, a viscosity of 105 sec. (falling ball test) and a ripeness of 9.5 Hottenroth. The said spinbath contained 6.5% H 80 17.5% Na SO and 5.0% ZnSO After leaving the spinbath, the spun threads were stretched in the air by 50% and taken up at a velocity of 35 meters per minute. The yarn was aftertreated in the conventional way. a

Physical properties of the yarn so manufactured were: the secondary swell value was 64%; the dry strength. was 3.2 g./denier; the dry elongation was 19%; and the cross sections of the threads showed a yarn of substantially all skin.

What is claimed is: 1. A process for the production of regenerated cellulose articles which comprises spinning a viscose solution into an aqueous acid coagulatingregenerating bath containing a zinc salt in the presence of about 0.01-1.0% by weight of an organic compound of the general formula:

wherein n is a whole number of to about 100.

2. A process for the production of regenerated cellulose articles which comprises spinning a viscose solution into an aqueous acid coagulating-regenerating bath containing a zinc salt in the presence of about 0.01-1.0% by weight of an organic compound of the general formula:

/CH=CH pl) CH--CH wherein n is a whole number of 10 to about 100.

3. A process for the production of regenerated cellulose articles which comprises spinning a viscose solution into an aqueous acid coagulating-regenerating bath containing a zinc salt in the presence of about 0.01-1.0% by weight of an organic compound of the general formula:

C H S-(C H 0) C H --OH wherein n is a whole number of 10 to about 100.

4. A viscose spinning solution in which there is incorporated between 0.01 and 1.0% of an alkali stable organic compound of the general formula:

C H -S -(C H O) C H -OH in which n is a whole number of 10 to about 100.

' 5. A viscose spinning solution in which there is incorporated between 0.01 and 1.0% of an alkali stable organic compound of the general formula:

wherein n is a whole number of 10 to about 100.

6. A viscose spinning solution in which there is incorporated between 0.01 and 1.0% of an alkali stable organic compound of the general formula:

wherein n is a whole number of 10 to about 100, R is selected from the group consisting of C H 1, C H and C H R is selected from the group consisting of S, CO0 and CONH, and R is selected from the group consisting of OH, OC H and CONHC H and compounds of the general formula:

wherein n is a whole number of 10 to about 100, R is selected from the group consisting of H, CH and C H X is selected from the group consisting of COC H CO, C6H4CO, and

and R' is selected from H, CH and OC H 8. A viscose spinning solution in which there is incorporated between 0.01 and 1.0% of an organic compound selected from the group consisting of compounds of the general formula:

wherein n is a whole number of 10 to about 100, R is selected from the group consisting of C H11, C H and C H R is selected from the group consisting of S, CO0 and CONH, and R is selected from the group consisting of OH, OC H and CONHC H and compounds of the general formula:

O( C H O C H -OR wherein n is a whole number of 10 to about 100, R is selected from the group consisting of H, CH and C l-I X isselected from the group consisting of COC H CO,

R .1 s R and R' is selected from H,'CH and OC H Callimachi Mar. 27, 1923 Collins Oct. 10, 1944 Cox Dec. 26, 1950 MacLaurin Apr. 22, 1952 Charles et a1. Dec. 29, 1953' Dietrich Dec. 7, 1954 Tachikawa Jan. 24, 1956 Pedlow Dec. 25, 1956 Edwards Jan. 15, 1957 Charles et a1. May 14, 1957 Mitchell Sept. 3, 1957 Lytton July 1, 1958 Lytton Aug. 26, 1958 Hollihan Sept. 16, 1958 Howsmon June 9, 1959 

7. A PROCESS FOR THE PRODUCTION OF REGENERATED CELLULOSE ARTICLES WHICH COMPRISES SPINNING A VISCOSE SOLUTION INTO AN AQUEOUS ACID COAGULTING-REGENERATING BATH CONTAINING A ZINC SALT IN THE PRESENCE OF ABOUT 0.01-1.0% BY WEIGHT OF AN ORGANIC COMPOUND SELECTED FROM THE GROUP CONSISTING OF COMPOUNDS OF THE GENERAL FORMULA: 